Inexpensive solutions to excessive calcium in water? (Distilled water would be expensive over time)

Distillate water is dead water. Add you water o2 with air stone like in fish tanks doing it. It’s make water alive and be very healthy.

Is your humidifier not filtered? I honestly get a build of minerals in my humidifier itself but I just clean it with vinegar every month and change the filter so the air it's blowing out into my veg room is clean and free if particulates. I guess that's why I'm not sure why you're getting actual particulates in your air. So maybe a bad filter? Or you could get a water softener but that's not all that cheap. Also RO water really isn't all that expensive. Try that maybe.